Two civilian police staff on Tyneside have been suspended as part of an inquiry into the suspected touting of illicit photographs of a naked artwork.
Close-up shots of volunteers are being touted
The close-up pictures are believed to have been taken from closed circuit TV footage of the work of American photo artist Spencer Tunick.
About 1,500 volunteers shed their clothes for a shoot taken at sunrise on the banks of the River Tyne last July.
Police are investigating reports of snapshots being offered in pubs.
A series of official Tunick pictures have formed the centrepiece of an exhibition, which has proved popular at Gateshead's Baltic arts centre, over the last two months.
Northumbria Police Deputy Chief Constable, David Warcup, said the force was investigating a complaint into the "possible misuse of CCTV footage".
He said: "If there is found to be any substance in these allegations we will take prompt and robust action. This is not the standard of behaviour expected from anyone employed by Northumbria Police.
"We have worked extremely hard over the years to ensure that the public can have confidence in the way in which we manage CCTV and we are determined that confidence will not be undermined, either now or in the future."
Last summer's shoot was Tunick's largest "installation" in the country and included zookeepers, postmen, midwives and a vicar.